You've heard of stores without cashiers and now comes a bar without bartenders. The new Brew Coop on Valencia Street is the first dedicated pour-your-own bar in San Francisco, California. Somewhat like Amazon Go, you pay at the entrance for a drink card, which interfaces with a radio frequency reader on the tap. It keeps track of how much you pour, but it cuts you off after two or three beers. If you're not drunk by then, the staff might let you put more on your card.